This invention relates to a power assisted steering gear and is particularly concerned with such a gear having a toothed part which is coupled by a rod to an axially extending input shaft and which is rotatably mounted for driving an output member in response to rotation of the input shaft about its axis. In such a gear the toothed part is usually in the form of a pinion or worm rotation of which, by rotation of the input shaft and through the rod, drives a toothed rack member or toothed sector member which comprises, or is coupled to, the output member. Conventionally a servo motor is associated with the output member to provide power assistance to displacement of that member and the flow of fluid under pressure to the servo motor is controlled by a valve which reacts between the toothed part and the input shaft and is responsive to rotation of the input shaft. Typically the valve and toothed part of a power assisted steering gear are operatively mounted in a housing with the input shaft extending from a side of the housing for connection, usually, to a steering column. It has hitherto been proposed with such a typical arrangement for the toothed part to be rotatably borne in the housing by a rolling or other type bearing and it is an object of the present invention to provide an improved bearing arrangement for the toothed part which arrangement is of a relatively simple construction and convenient to assemble (particularly with the pinion part).